I have the unique advantage (and sometimes disadvantage) this year of having a variety of grade levels in each classroom. No, I am not in a one-room schoolhouse, although it has the same feel. Currently I am teaching at a juvenile center- where at least I do not have to worry about students showing up to class, just how long they will remain at the center. As such I currently have a class with grades 4-11, one with 6-12 and my last group at 5-10. It has given me a huge insight on development of student thinking.

So with this in mind, my only intro to “Which One Doesn’t Belong” was that there was NO TALKING once the slide was shown- and that they needed to pick one shape and describe why it didn’t belong.

Great intro page, and the first one Christopher showed us at MCTM. Hearing Teachers talk about this page was awesome, I couldn’t wait to hear my student’s talk. One of the underlying themes this book brings to me is that we underestimate student’s ability to handle math concepts and vocabulary. My first hour did not disappoint on this. I was expecting answers like “the triangle because it has 3 sides” or “the diamond on the bottom left because it’s not completely red” because it’s the end of the year and my students are really shutting down (another driving reason for me to include some different activities/problem solving opportunities in class). Although I did receive both of those answers, it was the other reasoning I also received that set the tone for this activity. Parallelogram, Rhombus, Quadrilateral, Acute, Obtuse, Angle Sums, Orientation (yes, that word was used), Reflection, Symmetry, Rotation were all used. This first problem actually took 20 minutes to discuss as I got to sit back and record findings on the board as students lead discussions and pointed out differences. The fact that they know something IS wrong and they need to find it spun a new twist on the problem for students. Since they were not asked to *create* an answer, they felt this problem was accessible. Then one student asked “Mr. Anderson, there really isn’t a wrong answer for this is there?” I asked what he meant. He said “There are reasons that every figure could be chosen as the one that doesn’t belong.”- and there it is. I then asked them to find as many reasons why each one could be chosen, and students spent the next 5 minutes in great discussion, analyzing the figures and drawing on their previous mathematical experiences to classify properties. It was one of those warm, fuzzy feeling days.

As “homework” I assigned the task of each student making up their own Which One Doesn’t Belong page. When they create their own, they need to be able to identify at least two reasons each figure could be chosen- I can’t wait to see what they bring.

What a lovely report! Thanks for sharing it.